ARM/ARM64: KVM: Make kvm_psci_call() return convention more flexible

Currently, the kvm_psci_call() returns 'true' or 'false' based on whether
the PSCI function call was handled successfully or not. This does not help
us emulate system-level PSCI functions where the actual emulation work will
be done by user space (QEMU or KVMTOOL). Examples of such system-level PSCI
functions are: PSCI v0.2 SYSTEM_OFF and SYSTEM_RESET.

This patch updates kvm_psci_call() to return three types of values:
1) > 0 (success)
2) = 0 (success but exit to user space)
3) < 0 (errors)

Signed-off-by: Anup Patel <anup.patel@linaro.org>
Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

1 files changed, 7 insertions, 3 deletions

diff --git a/arch/arm/kvm/handle_exit.c b/arch/arm/kvm/handle_exit.c
index 0de91fc6de0f..4c979d466cc1 100644
--- a/arch/arm/kvm/handle_exit.c
+++ b/arch/arm/kvm/handle_exit.c
@@ -38,14 +38,18 @@ static int handle_svc_hyp(struct kvm_vcpu *vcpu, struct kvm_run *run)
 
 static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
 {
+        int ret;
+
         trace_kvm_hvc(*vcpu_pc(vcpu), *vcpu_reg(vcpu, 0),
                       kvm_vcpu_hvc_get_imm(vcpu));
 
-        if (kvm_psci_call(vcpu))
+        ret = kvm_psci_call(vcpu);
+        if (ret < 0) {
+                kvm_inject_undefined(vcpu);
                 return 1;
+        }
 
-        kvm_inject_undefined(vcpu);
-        return 1;
+        return ret;
 }
 
 static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run)